Ca a l'air pas mal

+   cmpi.w  #$F800,d0       ; Is it > $F800 ?
+   bls.s   \ramcall        ; No, so it is perhaps a ramcall (FirstWindow is not a romcall)
+       lea.l   4*7+6(sp),sp    ; Pop 7 registers + SR + Address of the 'crash'
+       subi.w  #$F800,d0   ; Clean data
...
+\ramcall:
+   subi.w #$F000,d0                ; Clean data

->

+   subi.w  #$F800,d0       ; Is it > $F800 ?
+   bls.s   \ramcall        ; No, so it is perhaps a ramcall (FirstWindow is not a romcall)
+       lea.l   4*7+6(sp),sp    ; Pop 7 registers + SR + Address of the 'crash'
...
+\ramcall:
+   addi.w #$800,d0                ; Clean data

?